Enabling Long‐Term Cycling Stability Within Layered Li‐Rich Cathode Materials by O2/O3‐Type Biphasic Design Strategy

Abstract Typical Li‐rich layered oxides are widely regarded as promising cathode candidates for high‐energy‐density Li‐ion batteries because of additional output capacities boosted by oxygen redox activities. However, its commercialized applications are hindered by serious capacity loss and voltage decay related to structural degradation upon cycling. Herein, a Co/Ni‐free biphasic O2/O3‐type layered cathode material is proposed, Li_0.9[Li_0.3Mn_0.7]O₂, which has been successfully prepared by the Li⁺/Na⁺ ion‐exchange strategy and characterized by the XRD Rietveld refinement and SAED as well as HRTEM analyses. O2/O3‐type layered cathode material with an approximate composition of 81% O2 and 19% O3 phases are confirmed. Furthermore, the biphasic cathode exhibits a high discharge capacity of 232 mAh g⁻¹ with capacity retention of 88.1% after 500 cycles at a current density of 200 mA g⁻¹. That is, volume changes of the O3‐type phase are effectively restricted during Li⁺ (de)intercalations, further enhancing the structural stability and suppressing the formation of spinel phase due to the biphasic structural design. Altogether, these findings prove the biphasic structural design is a feasible strategy to achieve Li‐rich cathode materials with high capacity and long‐term cycle stability.